Hangman's loop (5)
I believe the answer is:
noose
'hangman's loop' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for noose that I've seen before include "Hangman's rope" , "Snare made of rope" , "A loop for the hangman" , "Loop at the end of a rope" , "Loop in a lariat" .)